Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
  • H02P29/00—Arrangements for regulating or controlling electric motors, appropriate for both AC and DC motors
  • H02P29/0016—Control of angular speed of one shaft without controlling the prime mover
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T74/00—Machine element or mechanism
  • Y10T74/21—Elements
  • Y10T74/2117—Power generating-type flywheel

Definitions

• This invention relates to a method for attenuating oscillations of a rotating system comprising a driving rotary element and a driven rotary element operatively connected to the driving element to be rotated thereby, such oscillations being induced by the input torque of 10 the system deviating from the value corresponding to the torque required by the driven rotary element at a selec ⁇ ted rotational speed.
• the driving element can be a water 15 or wind driven turbine, an internal combustion engine or other drive engine
• the driven element can be an electric generator (dynamo) or other apparatus which should be kept accurately at a predetermined rotational speed without substantial oscillations.
• the generator preferably is a syn ⁇ chronous generator which should be driven at the syn- 25 chronous rotational speed in order to generate electric power at the predetermined frequency, usually 50 or 60 cps.
• the rotational speed thereof is maintained at the value corresponding to the frequency of the network to which
• Fig 1 is a diagrammatic view of a rotary system primarily comprising a turbine and a generator driven thereby; .
• Fig 2 is a block diagram of the attenuating system;
• Fig 3 is a diagram shewing the generator electro- dynamic torque response over the time on an input step torque and without any attenuation of the oscillations;
• Fig 4 is a diagram showing the instant value of the generator current over the time when the generator torque is oscillating according to Fig 3 and thus no attenuation of the oscillations is applied;
• Fig 5 is a diagram showing the derivative of the load angle of the generator over the time, corre- sponding to the conditions of Figs 3 and 4;
• Fig 6 is a diagram as that in Fig 3 when oscilla ⁇ tions are attenuated according to the method of the invention
• - Fig 7 is a diagram as that in Fig 4 corresponding to the conditions of Fig 6;
• Fig 8 is a diagram as that in Fig 5 corresponding to the conditions of Fig 6;
• Fig 9 is a diagram showing the attenuating torque over the time. Best Mode of Carrying Out the Invention
• a turbine 10 e.g. a wind turbine such as a turbine of the air screw type, is connected to a shaft 11 which is rotatably mounted in a conven ⁇ tional manner not shown.
• a generator 12 such as a syn- chronous generator is also connected to this shaft.
• a conventional speed regulator not shown, may be provided which senses the rotational speed and controls the turbine in dependence on the speed e.g. by adjusting the angle of the blades or vanes thereof (long term control) .
• the speed of the generator can also be governed by a network connected to the generator, to maintain the synchronous speed as is commonly applied.
• the rotary system comprises means for working the method according to the invention.
• These means comprise an eddy-current brake 13 including a rotating element 14 connected to the shaft 11, and a stationary element 15 surrounding the rotating element, which is mounted in a frame not shown.
• Said means may also comprise an energy storing de ⁇ vice 16 including a flywheel 17 which is rotatably journalled around its axis by means of bearings 18 so as to be rotatable in relation to the shaft 11 and in-
• the fly ⁇ wheel 17 can be driven by the shaft over a gearing 19, the input element of which is connected to the shaft 11-and the output element of which is connected to one part 20 of an eddy-current coupling, the other part 21 of which is connected to the flywheel 17.
• the gearing steps up the rotational speed of the shaft; the gearing ratio may be e.g. 1:2 the flywheel 17 thus being driven at a rotational speed, which is twice that of the shaft 11.
• a second eddy- -current coupling comprises one part 22.
• a set of slip rings 24 is arranged on the flywheel axis for connecting the coup ⁇ lings to an electric voltage source, the energization and de-energization of the couplings as well as the brake being controlled by the system disclosed in Fig 2. It may be noted that the flywheel 17, instead of being driven over the gearing 19, may be driven by a separate motor of any kind.
• the function of the eddy-current brake 13 may, especially for smaller torque oscillations, be taken over by the driving eddy-current coupling 20,21 acting in such a case as a brake.
• the eddy-current brake 13 may even in special cases be omitted altogether.
• the derivative of the load angle ⁇ of the generator is sensed by known means, not shown, and represents an acceleration or a deceleration of the shaft 11. As indicated by an arrow
• a signal representing the derivative of the load angle is supplied to a comparator 25 having two out ⁇ puts 26 and 27, for supplying a "yes" or “no" signal according to the relation . >0 to output 26 or output 27, respectively. If the value of ⁇ is positive a signal is supplied to a proportional integrator 28 via output 26, and if the value is negative a signal is supplied to a proportional integrator 29 via output 27.
• Each of these integrators is arranged to energize the brake 13 or the storage device 16, respectively, according to a predetermined relationship in dependence on the deriva- tive of the load angle ⁇ so as to compensate for an acceleration or deceleration of the shaft 11 causing oscillations of the shaft in either rotational direc ⁇ tion thereof.
• a positive derivative of the load angle (acceleration) will induce energization of the brake 13 in order to retard the shaft 11, while a nega ⁇ tive derivative of the load angle c (deceleration) will induce de-energization of the coupling 20, 21 and energization of the coupling 22, 23 in order to accel ⁇ erate the shaft 11 by means of the rotating flywheel 17 the rotational speed of which is higher than the rotational speed of the shaft.
• Fig 3 the generator torque response is shown over the time, the torque M being indicated on the ver ⁇ tical axis and the time being indicated on the horizon ⁇ tal axis.
• the diagram illustrates the conditions when no attenuation is applied to the rotating turbine generator system and it will be seen from the diagram that the generator torque due to an input step torque is oscillating to a considerable extent. These oscilla ⁇ tions are reflected in the instant value of the gener ⁇ ator current as shown in Fig 4 wherein the vertical
• the input generator torque may be brought to a constant level after one oscillation as will be seen in Fig 6 with a corresponding adjustment of the instant value of the generator current as seen in Fig 7. It is obvious that the oscillations may be totally reduced by increasing the magnitude of the attenuating torque.
• Fig 8 illustrates that the derivative of the load angle ⁇ of the generator is eliminated and the load angle thus is brought to a constant level.
• Fig 9 illustrates the attenuating torque over the time, and it may be noted that in this case only the brake 13 has been active and not the energy storing device 16.
• the load angle ⁇ and its derivative ⁇ may be taken not only from the shaft speed and its variations but also as an alternative from the electrical power or current from the generator or the mechanical shaft torque measured on the generator or turbine shaft.
• the system illustrated in Fig 1 can include also means limiting the effect of the brake and the energy accumulating source and this system also can be further developed as is well known in the art within the scope of the present invention.

Landscapes

• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Control Of Eletrric Generators (AREA)
• Wind Motors (AREA)
• Connection Of Motors, Electrical Generators, Mechanical Devices, And The Like (AREA)

Applications Claiming Priority (2)

Publications (1)

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ID=20337288

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Country Status (9)

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Citations (3)

Family Cites Families (4)

• 1979
  • 1979-02-14 SE SE7901293A patent/SE424232B/sv unknown
• 1980
  • 1980-02-11 GB GB8004469A patent/GB2042224B/en not_active Expired
  • 1980-02-13 JP JP1558180A patent/JPS55123035A/ja active Pending
  • 1980-02-13 WO PCT/SE1980/000043 patent/WO1982003707A1/en unknown
  • 1980-02-13 IT IT19888/80A patent/IT1140579B/it active
  • 1980-02-13 CA CA000345500A patent/CA1153808A/en not_active Expired
  • 1980-02-13 FR FR8003169A patent/FR2449238A1/fr active Granted
  • 1980-02-14 DE DE19803005561 patent/DE3005561A1/de not_active Withdrawn
  • 1980-07-15 US US06/209,104 patent/US4326158A/en not_active Expired - Lifetime

Patent Citations (3)

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